A conventional system and a method of assessing and identifying a failed state of components of a communication network have been disclosed (for example, Japanese Laid-open Patent Publication No. 8-307524). The conventional technique disclosed therein is as follows. That is, a data acquiring/processing module operates to acquire and process a warning message signal transmitted over a communication network and to generate an abnormal condition signal. Next, the module operates to generate a direct risk signal and an indirect risk signal on the basis of the generated abnormal condition signal, an external condition signal and registered reference data. Then, the module operates to combine the direct risk signal with the indirect risk signal as support to assess a risk involving a component which is in an abnormal condition and to display a risk signal of the component. The module also operates to calculate and display a risk signal of a sub-network on the basis of disconnection influence data and failure influence data involving the sub-network of the communication network. The module further operates to adjust risk calculations in which various types of maintenance activities are considered in order that the communication network may determine how it responds in accordance with these maintenance activities.
In addition, a conventional technique of fetching a device alternative to a failed device (hereinafter, referred to as a failure alternate device) from another high-redundancy logic group to recover redundancy with no need of hot spare patrol is also disclosed (for example, Japanese Laid-open Patent Publication No. 10-260789). In this conventional technique, in case of RAID-1 of a mirror device correspondence type, a configuration control section constructs a first logic group in which the same data is stored in N (=2) devices to duplicate the data and a second logic group in which the same data is stored in N+1 (=3) devices to triplicate the data as the logic groups of a device array unit. A failure processing section fetches one of the devices in the high-redundancy second logic group into the first logic group in the case that one device in the low-redundancy first logic group has failed and its redundancy is lost, to reconstitute data as the failure alternate device, thereby recovering the redundancy of the first logic group. Further, a conventional technique of duplicating data in a logical volume to perform logical volume allocation without fixing the role of a physical module is disclosed (for example, Japanese Laid-open Patent Publication No. 2005-004681). In this conventional technique, an integrated management module selects a module having a storage device of a designated range as an object to which slice data is to be allocated on the basis of a request from a client, allocates primary logical volumes to modules having slice areas to which no volume is allocated in the one-to-one correspondence by the number necessary in a round robin system and allocates secondary logical volumes to modules which have been selected in accordance with a predetermined assessment function by the number necessary in the system under a constraint condition that the secondary logical volume is not allocated to the module having the primary logical volume and handling the same data area as a module to which the secondary logical volume is allocated.